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TLC vs. QLC SSDs: What Businesses Should Know, Expert Guidance from Epis Technology

As more and more businesses use flash storage to speed up virtual machines, databases, and NAS workloads, the argument between TLC and QLC SSDs has grown. SSDs greatly lower latency and improve performance, but not all types of NAND act the same way in real life. Epis Technology often helps companies deal with these differences by making sure they choose storage media that meets Synology deployments’ and other IT infrastructures’ performance, endurance, and long-term reliability standards.

This guide explains how different types of NAND affect performance and shows why it’s important for businesses to choose the right SSD to keep things running smoothly.

Understanding Different Types of NAND Flash

SSDs use NAND flash memory cells to store data. The type of cell is based on how many bits it has:

  • Single-Level Cell (SLC): 1 bit per cell; best performance and durability
  • MLC (Multi-Level Cell): 2 bits per cell; good balance of speed and endurance
  • TLC (Triple-Level Cell): 3 bits per cell; this is the most common type today.
  • QLC (Quad-Level Cell): 4 bits per cell; This is the most dense and least durable.

TLC has become the most popular type of NAND because the industry wants more storage space and lower prices. QLC is still getting a lot of attention as a cheap alternative to HDDs. However, higher density naturally lowers endurance and consistent write performance, which are very important for enterprise NAS, virtualization, and production workloads.

This is where Epis Technology’s important knowledge comes into play. Epis Technology helps businesses stay away from SSDs that have great burst speeds but quickly lose performance when used continuously by looking at workload patterns like sequential writes, random I/O, and caching behavior.

How SSDs Keep Up Their Performance

New SSDs use techniques like SLC caching to hide the problems that come with slower NAND. Even QLC drives can seem very fast when there isn’t much work to do because they temporarily treat parts of NAND as high-speed pseudo-SLC.

Epis Technology, on the other hand, says that real-world operations, especially in Synology NAS environments, often go beyond these short bursts, which can cause performance to drop when cache regions fill up. When choosing drives for infrastructure that is important to the business, this difference is very important.

Synthetic tests only tell part of the story about burst performance

Many TLC and QLC drives show great speeds when tested with tools like CrystalDiskMark or AJA System Test. When drives are empty, QLC caching works really well, looking a lot like TLC and sometimes even better than enterprise SSDs.

Epis Technology, on the other hand, says that synthetic benchmarks don’t show how things are really used. They don’t accurately model the long-term virtualization workloads, high IOPS needs, or multi-user access that are common in production settings.

Performance at 65% of its full capacity

When drives are only partially full, which is a much more likely situation, performance starts to differ:

  • Enterprise SSDs: Reliable and stable
  • Consumer TLC: Small drops, but still okay
  • QLC SSDs: Big steps back, especially in how consistently they read data.

When systems reach normal operating fill levels (60–80%), where caching space gets smaller and raw QLC speeds take over, Epis Technology’s field deployments get the most complaints about QLC drives. This can cause NAS devices to have latency spikes that are hard to predict, which can make VMs less responsive and slow down business operations.

The Steady-State Reality of Full Drive Performance

A full-drive test shows how well the system really works when the cache layers are full. This simulation is especially useful for Synology SSD caching, where drives are always taking in data and don’t have much time to recover.

  • Enterprise SSDs: Keep the throughput high and the latency low
  • Consumer TLC SSDs: Start off fast, then drop off quickly as the cache runs out
  • QLC SSDs: Slow down to speeds like those of an HDD, or even worse.

This is one of the reasons why Epis Technology always suggests using enterprise-grade SSDs in Synology deployments and environments with heavy use. Enterprise drives are more reliable, consistent, and long-lasting than consumer models that use QLC.

Why Epis Technology Suggests Synology Users Use Enterprise SSDs

Epis Technology helps companies choose SSDs that meet their real-world needs, not just theoretical benchmarks. Epis Technology looks at things like:

  • Patterns of I/O (random vs. sequential)
  • Write strength
  • Expected life span of the drive

The role of NAS is to act as a cache, a VM host storage, and a backup repository.

Needs for performance vs. budget

Because enterprise SSDs have:

  • Higher endurance (DWPD ratings)
  • Better management of heat
  • Performance that is stable and predictable
  • Better long-term writing behavior
  • Firmware that works well in 24/7 settings

Epis Technology adds these drives to Synology storage solutions to make sure that VMs, containers, databases, and backup infrastructures are always up and running, have low latency, and perform well over time.

Epis Technology helps businesses avoid these problems by making storage systems that are based on enterprise SSDs and properly tuned Synology environments. Epis Technology makes sure that storage systems are always fast, reliable, and ready for mission-critical operations by doing expert performance analysis, endurance planning, and hardware matching.

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